When tig welding stainless steel tubing usually only the outside of the tube gets argon gas shielding, preventing the molten metal from oxidizing while the inside of the tube gets exposed to heat and the outside air. Exposing the hot molten metal results in a black powdery sugar texture on the inside of the tube leading to a weak joint and obstructed flow in the tube...to prevent this, backpurging is employed, wherein argon gas is introduced inside the tubing, shielding the other side of the weld...
first, cover one end of the tube with kapton tape ( high temp tape that won't burn up during welding)
then pierce a small hole for the argon to exit to....
tackweld the tubes together and install the argon hose and cap to the other end, and allow argon to flow through aound 8 to 10 lpm...and begin welding...
Re: backpurged tig welding of stainless steel tubing
the outside weld...
cutting the tube in half reveals the backside of the weld....
sorry for the blurry pictures, still need to learn photography.....hth
Re: backpurged tig welding of stainless steel tubing
Hey bro butch11a,
I don't have yet a TIG weld machine and really have no idea yet of the tip you are showing but really thanks for the tip regarding backpurging during Tig application but looking back at the pics you showed, did you just simply butt weld the two pipes/tubings without leaving a possible 1/16" of an inch gap between the edges of the tubing ??
I've been watching videos on Tig welding applications and also reading articles regarding this, usually I see when joining two pieces of tubings, a gap is always provided between the two ends of the tubing to be welded. Am I missing here something ?
Bro please do continue giving some tips and tricks or other useful information regarding its applications.
Thanks bro,
CIGWELD Weldskill 250 amp Mig Welder
AHP Alpha-TIG 200X welder
HITRONIC 300 Amp DC Inverter IGBT Welder
YAMATO 300 amp AC Stick Welder
YAMATO 200 amp DC Inverter IGBT Welder
DeWALT Chopsaw
HOBART and ESAB Welding Helmets
cloned STIHLs
MS 044 chainsaw
MS 070 chainsaw
Re: backpurged tig welding of stainless steel tubing
you're right sir rosy, the tubes are butt welded together, usually we work on 1 to 1.5 mm tubing and the tig welder is powerful enough to penetrate through 100% of the thickness of the metal. for thicker pipes like sched 10 to sched 40, the ends need to have a gap and or bevelled for the weld to penetrate through. Fusion welded joints usually are as strong as the base metal which is strong enough for our application, sometimes we use 0.6 to 0.8mm filler wire to make the joints stronger and look nicer too....which is why on high end projects we do backpurging to ensure that the welds pass all the way through the metal while leaving a smooth internal surface.....its like having someone weld from inside the tube as well... hth
Re: backpurged tig welding of stainless steel tubing
Yes bro butch11a, I guess working on pipes/tubings of 1mm or 1.5mm will not need any beveling and a certain gap unless it is really a very thick walled tubing. That is what I also do with tubing of 1mm or 1.5 or even up to 2.0mm thick wall, even with GI pipes, no more beveling and gaps, just straight butt joints using a stick DC weld machine, increase ko na lang and ampere setting para mas mainit at maka penetrate yun welds.
Thank again bro !!!
CIGWELD Weldskill 250 amp Mig Welder
AHP Alpha-TIG 200X welder
HITRONIC 300 Amp DC Inverter IGBT Welder
YAMATO 300 amp AC Stick Welder
YAMATO 200 amp DC Inverter IGBT Welder
DeWALT Chopsaw
HOBART and ESAB Welding Helmets
cloned STIHLs
MS 044 chainsaw
MS 070 chainsaw
Re: backpurged tig welding of stainless steel tubing
Great info bro Butch.
How about the source of back purge gas ... do you need a separate tank and flow meter?
Millermatic 180 Autoset Mig Welder
Miller Spoolmate 100 Spool Gun
Victor Firepower 350 Oxy Ace Outfit
3M Speedglas 9002X AD Helmet
Makita LC1230 Dry Cut Saw
Ingersoll Rand Air Tools
Snap On Tools
Metabo Power Tools
Norseman Drill Cutting Tools
Bosch Power Tools
3M PPS
Re: backpurged tig welding of stainless steel tubing
yes jay, i use my spare argon regulator and tank so as not to affect the flowrate on the tig torch, but a wye set up on a single regulator and dual flowmeters will do, just have to experiment with the joint flowrates..... good thing i was able to purchase flowmeters from hmr a long time ago.....
and sir rosy, having no gap means more accurate positioning of the tube/elbows to the desired orientation, which is why i prefer butt welded bevels against gaps when working on thick materials...
Re: backpurged tig welding of stainless steel tubing
Where to buy those thermal tapes? Thanks
Sent from my ME173X using Tapatalk
Using Tapatalk
